Optically active alcohols represented by formula (I): ##STR3## wherein R.sub.1 is an alkyl group having from 2 to 11 carbon atoms, an alkenyl group having from 3 to 11 carbon atoms, an alkadienyl group having from 6 to 11 carbon atoms, a cyclohexyl group, an cyclohexylmethyl group, or a cyclohexylethyl group, provided that the olefin in the alkenyl group or alkadienyl group is not conjugated to the olefin at the 2-position thereof; and * means an asymmetric carbon atom,
are useful not only as intermediates for the production of perfumes and vitamin E but also as liquid crystal materials.
Several methods of asymmetric synthesis have been available for producing such optically active alcohols, for example, (1) a method starting with naturally occurring optically active isomers; (2) a method utilizing microbial asymmetric hydrogenation; and (3) a method involving asymmetric hydrogenation in the presence of a specified catalyst. In particular, as a method for obtaining the optically active alcohol of formula (I) by asymmetric synthesis of an olefinic alcohol represented by formula (II): ##STR4## wherein R.sub.1 is the same as defined above, it is reported in Chemistry Letters, pp. 1007-1008 (1985) that the asymmetric synthesis is performed by asymmetric hydrogenation of geraniol or nerol in the presence of, as a catalyst, a rhodium-optically active phosphine complex.
On the other hand, as to asymmetric hydrogenation using, as a catalyst, a ruthenium complex, it is reported
in J. Chem. Soc., Chem. Commun., pp. 922-924 (1985) and European Pat. No. 174,057A that N-benzoylphenylalanine with an optical purity of 92% was obtained from 2-.alpha.-benzoylaminocinnamic acid and (3R)-3-methyl- or (3R)-3-phenyl-.gamma.-valerolactone with an optical purity of 39% or 33% from 3-methyl- or 3-phenylglutaric anhydride, respectively.
Among these methods of asymmetric synthesis, according to the method (1) starting with naturally occurring optically active isomers or method (2) utilizing microbial asymmetric hydrogenation, though desired alcohols with high optical purities can be obtained, not only is the absolute configuration of the resulting optically active alcohols limited to a specific one, but also it is difficult to synthesize their enantiomers. Further, in accordance with the asymmetric hydrogenation of allyl alcohol derivatives using a rhodium-optically active phosphine catalyst, not only are the optical purities of the resulting alcohols not yet satisfactory, but also since metallic rhodium to be used is expensive due to limitations in place and quantity of production when used as a catalyst component, it forms a large proportion in cost of the catalyst, ultimately resulting in an increase in cost of the final commercial products.